Petroleum distillates containing ammonium mahogany sulfonates and oil soluble carboxylic acids to prevent corrosion



Patented Mar. 24, 1953 UNITED STAT OFFICE Franklin M. Watkins, Flossmoor, 111., assignor to Sinclair Refining Company, New York, N. Y., a corporation of Maine N Drawing. Application November 14, 1950, Serial No. 195,702

8 Claims. 1

My invention relates to light petroleum distillate fractions to which anticorrosive properties have been imparted by the addition of exceedingly small proportions of a mixture of ammonium mahogany sulfonates and a higher, mineral oil-soluble carboxylic acid.

Rust frequently occurs in light oil products pipe lines, storage tanks and even in the equipment wherein such products are ultimately used, because of the traces of moisture that are inevitably present in the oil. For example, although gasoline as it leaves the refinery is usually free of occluded moisture it may contain as much as 0.005% to 0.01% of dissolved moisture. Part of this dissolved moisture separates when the light oil product is chilled and settles as a separate liquid phase beneath the main body of oil. Water may also enter oil systems along with air through partially filled tanks provided with breather devices. As such a tank cools, for example at night, its contents contract and moisture-laden air drawn in. This moisture condenses on the wall of the tank, settles to the bottom and dried air is expelled when the contents of the tank again warm up, as from the heat of the sun the next day. Repetition of this cycle eventually leaves appreciable amounts of moisture at the bottom of the tank.

As is obvious, the rust that forms permanently injures expensive equipment and there is additional loss in terms of replacement costs of such equipment and operating time lost during such replacement. For example, Where rust forms on interior surfaces of product pipe lines and no effort is made to prevent it, this rust formation may reduce carrying capacity of the pipe by more than 12 per cent in one year. In addition to the decrease in life of rusted equipment such as storage tanks, there is danger of trouble in engine operation from failure of fuel carrying equipment and the likelihood of rust particles clogging carburetors or injecting devices for motors and burners, for example.

In my co-pending application Serial No. 86,121, filed April '7, 1949, now Patent No. 2,594,266, issued April 22, 1952. I disclose the use of ammonium mahogany sulfonates in light petroleum distillate fractions to impart anticorrosive properties and thereby susbtantially overcome these problems. Small amounts of the sulfonates, e. g. 0.5 to 50 pounds on the oil-free basis per one thousand barrels, are added to the oil, which gives excellent protection against corrosion to metal surfaces in contact with such compositions.

I have now found that the proportions of ammonium mahogany sulfonates required for satisfactory protection are significantly reduced by addition of a small amount of a higher oil-soluble carboxylic acid, indicating surprising synergistic action. Thus, when the higher carboxylic acid inhibitor is added to the light oil in minute amount, only about one half, or less, as much of the ammonium mahogany sulfonates are re quired to effectively inhibit corrosion and the total quantity of inhibitor material added is still only a fraction of the sulfonate that would ordinarily be required alone. For example, about four pounds of ammonium mahogany sulfonates on the oil-free basis are required to effectively inhibit 1000 barrels of a particularly unresponsive fuel oil, but by adding about 0.25 lb. of the carboxylic acid only 1.5 pounds of the sulfonates are required under the same conditions.

The reason for the synergistic activity between the ammonium mahogany sulfonates and the higher carboxylic acids is not understood. Possibly, the sulfonates and acids are selectively adsorbed on different portions of the metal surface, although some areas are able to accommodate either, thus more effectively forming an uninterrupted continuous protective layer. I have observed, however, that with certain fuels it is diflicult to obtain complete protection at reasonable concentration with only one of the inhibitors. In such circumstances, I believe that the inhibitor is adsorbed on only certain areas of the metallic surface to the extent of forming an effective protective film, and is incapable of displacing" some unusual constituents in the oil which form as films on other areas. These impurities are incapable of preventing rust formation on such areas but prevent the inhibitor from forming a protective layer. Accordingly, it is my belief that the complete rust protection obtained from use of the combination of inhibitors may be due to the fact that the secondary inhibitor is capable of displacing the adsorbed impurities and so protects such secondary areas.

According to my invention, a small amount of ammonium mahogany sulfonate or mixture thereof and a higher carboxylic acid is added to the light petroleum distillate fraction. The ammonium mahogany sulfonates may be obtained by reaction of ammonia with sulfuric acidtreated hydrocarbon oils, i. e. by ammoniation of mahogany acids. Such ammonium mahogany sulfonates possess appreciable solubility in both water and hydrocarbon oils. In the practice of my invention, I customarily employ the ammonium sulfonates as a concentrate in the oil from which they are derived. A typical concentrate may have, for example, a sulfonate concentration of about per cent by weight and may test as follows:

Gravity API 28.0 Flash F 385 Fire F 445 Viscosity at 100 SUS 416 Viscosity at 130 SUS 163 Viscosity at 210 SUS 49.2 Viscosity index 90 Color 4 Nitrogen (percent) 0.265 Acid number 9.0 Sulfur (percent) 0.60

This particular concentrate was prepared by treating a Mid-Continent neutral oil with four successive dumps of oleum, a total of 120 pounds of the oleum being used for each barrel of oil. Following removal of the separable sludge after the last dump of oleum, the acid oil was blown with air to remove sulfur dioxide and settled to remove substantially the last trace of sludge. Thereafter the oil was mixed with 0.5 per cent by weight of water and neutralized with an excess of anhydrous ammonia. Finally the oil was heated to a temperature of 280 F. to dehydrate it, and filtered to obtain the above product.

Although the ammonium mahogany sulfonates are advantageously employed in the oil solution in which they are prepared, the sulfonates may be recovered by extraction with a low molecular weight alcohol, such as isopropanol or ethanol, followed by distillation for use in the oil-free form. The distillation procedure is disclosed in Patent No. 2,461,371, issued February 8, 1949, to Eldon B. Cole. A lower molecular weight oil soluble alcohol, such as isopropanol, or aniline is advantageously added to the sulfonate solution in small amounts to improve the stability thereof. Such ammonium mahogany sulfonate solutions of greater stability are disclosed in the United States patents of M. P. Kleinholz and T. P. Hack, Nos. 2,522,518 (alcohol addition) and 2,522,519 (aniline), both issued September 19, 1950.

Added in conjunction with the sulfonates are rust inhibitor compositions based upon higher oilsoluble carboxylic acids, particularly the oxygenated carboxylic acids. By higher carboxylic acids I mean organic acids having at least 10 carbon atoms per molecule, so that sufiicient oil solubility is obtained as well as desirable rust inhibiting characteristics. In particular, the higher carboxylic acids comprising alpha-hydroxy decanoic acid or esterified alpha hydroxy aliphatic acids, such as that of lauric acid, or alpha-acyloxy carboxylic acids, such as lauroylacetic acid, or synthetic C1s+ acids produced by the oxidation of petroleum wax are advantageous- 1y employed.

Esterified alpha hydroxy aliphatic acids are prepared by condensation of two molecules of the acid, e. g., lauric acid, with elimination of 1 molecule of water and have the following general formula:

, The use of these products alone in oils to prevent rust wherein the aliphatic radical contains from 10 to 18 carbon atoms is disclosed in Patent No. 2,403,928, dated July 16, 1946, to Milton P. Kleinholz. Acyloxycarboxylic acids having at least 10 carbon atoms are also useful in conjunction with the sulfonates. In the copending applications of Stephen J. Wayo, Serial Nos. 140,549 and 140,550, filed January 25, 1950, useful acids of this type, particularly acyloxyacetic acids such as lauroyloxyacetic acid, are disclosed. Also useful are synthetic acids of unusually high molecular Weight, prepared by oxidation of C34 to C55 microcrystalline waxes under controlled conditions. Such acids are essentially monocarboxylic and contain upwards of eighteen carbon atoms per molecule. These compound and the preparation thereof are disclosed in the copending application of John Walter Nelson, Serial No. 157,177, filed April 20, 1950.

The ammonium mahogany sulfonates and higher carboxylic acids may be added separately or as a mixture to the light petroleum distillates. By light petroleum distillate I mean petroleum distillates of a viscosity not exceeding that of gas oil. In this way light oils such as gasoline, kerosine or distillate fuels, e. g. home heating fuels or diesel oils, are effectively given anticorrosive properties. Generally, the amount of each to be added will vary depending upon the exact acid inhibitor used conjointly with the sulfonates since the combination will determine the extent of the synergistic action. Ordinarily, amounts of the ammonium mahogany sulfonates in the range of 0.2 to 2.5 pounds per one thousand barrels on the oil-free basis and about 0.05 to 5.0 pounds of the higher carboxylic acid per one thousand barrels are used. Howeveig'upper limits of about two pounds of the sulfonates with a maximum of one pound of the acid usually provide excellent protection at very low cost.

In particular, I have found that combination of the sulfonates with lauroyloxyacetic acid are particularly satisfactory. In this regard, about 1.5 pounds of ammonium mahogany sulfonates on the oil-free basis and 0.1 pound of lauroyloxyacetic acid per one thousand barrels of light oil is highly advantageous.

Thus, the synergistic admixture of ammonium mahogany sulfonates and carboxylic acids I use affords low cost rust protection when incorporated in light petroleum distillate fractions. It does not require multiple injections into the oil treated-only one injection is needed. This is an important advantage particularly in providing rust protection in light oil products pipe lines which are of great length. Since the combination is chemically stable and does not become inert through oxidation there is no predictable limit to the effectiveness of the anticorrosive product, from the pipe line to the ultimate condenser. That is, the protection against rusting will extend, after a single injection following preparation of the oil, beyond the trunk lines used to transport it from the refinery to bulk distribution plants. The additional equipment subject to protection against rusting includes bulk and service-station equipment, tank cars, tank trucks, and customer equipment. In addition to the increase in useful life due to rust inhibition, there is the additional advantage to the ultimate user of less trouble from rust particles, such as plugging of filters and. orifices of carburetors, diesel-engine injectors, and gun-type burners of household heating units. The oil compositions containing it can be handled easily with ordinary equipment and since they give homogeneous, non-toxic products there is no danger to personnel.

The following examples are presented in order to illustrate more clearly the improved anticorrosive products of my invention.

The inhibitors were added to distillate fuels, (gasoline, kerosine and distilled heating oils) sulfonates per 1,000 barrels. Table I also shows activity of four secondary inhibitors when. used alone. Alpha-hydroxy decanoic acid when used alone does not give complete rust protection.

and tested by a modification of ASTM test Oxidized wax acids are more potent, and sub- D665-4'7T: Rust-Preventing Characteristics of stantially complete protection can be obtained Steam-Turbine Oil in the Presence of Water. when as much as 5 pounds is used. Esterified In this modified procedure, a freshly ground rust alpha hydroxy lauric acid and lauroyloxyacetic test coupon consisting of a 4; inch diameter by acid give complete protection using 2 pounds of 5 inches long mild steel rod is suspended in a inhibitor. Table I further shows that though 400-1111. beaker equipped with astirrer and placed 12 pounds of sulfonates alone gave only a 3+ in a temperature controlled bath capable of result, addition of 1 pound alpha-hydroxy maintaining the temperature at 101: 1 F. The decanoic acid, 1 pound oxidized wax acid, 1 test fuel (350 ml.) is added and stirred for thirty pound esterified alpha hydroxy lauric acid or minutes to allow rust inhibitor to precoat the 15 0.05 poun l r yloxyacet i av ubst ntest specimen. Part (50 ml.) of the test fuel is tially complete protection. then removed and 30 cc. of distilled water is Table II illustrates the Occu e ce o a y added, and the mixture stirred for 3 A hour test gistic effect using a kerosine fraction. This is an period. At the end of this period, the coupon is u u tock in that fian y mplete D removed, dried with suitable solvents, inspected tection is ot Obtained W e as muc as 70 and rated according to the following scale: pounds 03 Sulfonate is used- I an average kerorust sin; sgcgck comoletef: prggectirn woulali (llooeoolgtaimled W1 poun s o s ona e per arre s. 'gj gz gfzg g i fig gzgg a maxlmum of Complete protection was not obtained using as than 5% of surfac area covered by 145 much as 4 pounds of wax acids. However, subrust. stanti ally complete protection resulted from the B5 to of surface area covered by rust. combmatlon tihtaise mhlbniors' Table usrates the synergistic efiect in a No. 2 C 25 to 50% of Surface area covered by rust fuel oil Table III shows that the su fonates l D50 to 75% of surface area covered by rust. p us E 75 to 1007 of Surface area covered b st oxidized wax ac1ds or lauroyloxyacetic acid has 0 y m nearly the same activity in fuel oil as described The test conditions are substantially more seon Table I in gasoline. vere than ordinary conditions encountered so Tables IV and V show the use of a carboxylic the results give a clear indication of the effectiveacid preparation known as Santolene C in conness of the inhibitor mixture. Throughout the 5 junction with the ammonium mahogany sulfotest and accompanying description the ammonates. Santolene C is a mixture of a higher nium mahogany sulfonates were used as the 10 mineral-oil soluble carboxylic acid, a small per cent by weight solution described in the amount of an organic phosphorous derivative specification. and about 30% by weight of kerosine, and has Examples of results available from tests using 40 the following properties: gasoline plus mixtures of inhibitors are shown e on Table I. According to Table I a regular grade g ;g g f. gasoline used for test purposes gave D test when viscoity 0' YE no inhibitor was present. When as much as 25 Viscosity at 52 pounds of the sulfonates per 1,000 bbls. was used Pour Point 0 an A test rod result was obtained. As a result, Acid u 88 o it is interesting to note that this sample of gassapcnification Na oline is slightly less susceptible to the sulfonates Sulfur percent 006 than an average stock; an average gasoline s Nitrogen, percent 0.006 completely inhibited with about 20 pounds of Phosphorous, percent 0.33

Table I 10% Amm v g gg iit-QZ 325.3%? iittfiiii itiiili a Cone. Conc Cone. Cone. Conc. Lbs./ Bat Lbs./ Bat- Lbs./ Rat- Lbs./ Rat- Lbs./ Rat- 1,ooo mg 1,000 mg 1,000 ing 1,000 ing 1,000 ing Bbls. Bbls. Bbls. Bbls. Bbls.

Efiect of each of the inhibitors alone in a regular grade gasolme.

Combined efiect of one of the inhibitors with the ammonium mahogany sulfonates in the same gasoline.

Table II figfi gi Microcn stallinc Sulfonates Wax Aclds C oncentra- Concentration, Lbs./ Rating tion, Lbs./ Rating 1,000 Bbls.f 1,000 Bbls.

8 the distillate fractions amounts in the range approximating 0.2 to 2.5 pounds of ammonium mahogany sulfonates on the oil-free basis and 0.05 to 5.0 pounds of a higher oil soluble carboxylic acid corrosion inhibitor selected from the group consisting of acyloxycarboxylic acids having at least 10 carbon atoms per molecule, esterified alpha hydroxy aliphatic acids wherein the aliphatic radical contains from 10 to 18 carbon Efiect of each of the in- 20 05 hibimsaloneinakew 2.0 13+ 10 atoms per molecule and synthetic fatty aclds sine fraction 4.0 B+ having upwards or 18 carbon atoms per molecule Combined efiectoiboth g3 2 gii and prepared by oxidation of C34 to C55 micro- 20 .2 gitcrystalline waxes under controlled conditions, 20 each per one thousand barrels of petroleum distillate.

Table III 10% Ammonium M- t L 1 a Maho y i lClOClYS i116 auroy OQIY (lo 16 sulfogates Wax Acids A 1d ('lorticentra- Ooncentra- Concentraion, ion, on, 0 Lbs/1,000 Ratmg Lbs/1,000 Ratmg Lbs.1,000

Bbls. Bbls. B ls.

Efiect of each of the inhibitors alone in a No. 2 fuel oil Combined efiect of one of the inhibitors with the ammonium mahogany sulfonates in the same fuel oil Table IV 10% Ammonium Mahogany Santolene C Sulfonates Concentra- Concentra tion, lbs./ Rating tion, lbs./ Rating 1,000 bbls. 1,000 bbls.

Effect of each of the inhibitors alone in gasoline Combined effect of both 'bitors in the same gasoline Table V Ammonium Mahogany Santolene G Sulionates Concentra- Concentration, lbs./ Rating tion, lbs./ Rating 1,000 bbls. 1,000 bbls.

Efiect of each of the inhibitors alone in #2 Fuel Oil Combined effect of both inhibitors in the same #2 Fuel Oil Iclaim:

1. Light petroleum distillate fractions into which have been incorporated in synergistic proportions to impart anti-corrosive properties to 2. A fraction according to claim 1 wherein the carboxylic acid is an acyloxycarboxylic acid having at least 10 carbon atoms per molecule.

3. A fraction according to claim 1 wherein the carboxylic acid is an acyloxyacetic acid having at least 10 carbon atoms per molecule.

4. A fraction according to claim 1 wherein the carboxylic acid is an esterified alpha hydroxy aliphatic acid wherein the aliphatic radical contains from 10 to 18 carbon atoms per molecule.

5. A fraction according to claim 1 wherein the carboxylic acid is a synthetic fatty acid having upwards of 18 carbon atoms per molecule and prepared by oxidation of C34 to C55 microcrystalline waxes under controlled conditions.

6. Light petroleum distillate fractions into which have been incorporated in synergistic proportions to impart anti-corrosive properties to the distillate fractions amounts in the range approximating 1.0 to 2.0 pounds of ammonium mahogany sulfonates on the oil-free basis and 0.05 to 1.0 pound of a higher oil soluble carboxylic acid corrosion inhibitor selected from the group consisting of acyloxycarboxylic acids having at least 10 carbon atoms per molecule, esterified alpha hydroxy aliphatic acids wherein the aliphatic radical contains from 10 to 18 carbon atoms per molecule and synthetic fatty acids having upwards of 18 carbon atoms per molecule and prepared by oxidation of C34 to C55 microcrystalline waxes under controlled conditions, each per one thousand barrels of petroleum distillate.

'7. Light petroleum distillate fractions into which have been incorporated in synergistic proportions to impart anti-corrosive properties to the distillate fractions amounts in the range approximating 0.2 to 2.5 pounds of ammonium 9 mahogany sulfonates on the oil-free basis and REFERENCES CITED 0.05 to 01 pound of lauryloxyacetic acld, e The following references are of record in the per 1000 barrels of petroleum distillate. file of this patent:

8. Light petroleum distillate fractions into which have been incorporated 1.5 pounds of am- 5 UNITED STATES PATENTS monium mahogany sulfonates on the oil-free basis and 0.1 pound of lauryloxyacetic acid, each gg 32 Jul 3 per 1000 barrels of petroleum distillate. 2533300 Watkins 1950 FRANKLIN M. WATKINS 10 2,533,302 Watkins Dec. 12, 1950 

1. LIGHT PETROLEUM DISTILLATE FRACTIONS INTO WHICH HAVE BEEN INCORPORATED IN SYNERGISTIC PROPORTIONS TO IMPART ANTI-CORROSIVE PROPERTIES TO THE DISTILLATE FRACTIONS AMOUNTS IN THE RANGE APPROXIMATING 0.2 TO 2.5 POUNDS OF AMMONIUM MAHOGANY SULFONATES ON THE OIL-FREE BASIS AND 0.05 TO 5.0 POUNDS OF A HIGHER OIL SOLUBLE CARBOXYLIC ACID CORROSION INHIBITOR SELECTED FROM THE GROUP CONSISTING OF ACYLOXYCARBOXYLIC ACIDS HAVING AT LEAST 10 CARBON ATOMS PER MOLECULE, ESTERIFIED ALPHA HYDROXY ALIPHATIC ACIDS WHEREIN THE ALIPHATIC RADICAL CONTAINS FROM 10 TO 18 CARBON ATOMS PER MOLECULE AND SYNTHETIC FATTY ACIDS HAVING UPWARDS OF 18 CARBON ATOMS PER MOLECULE AND PREPARED BY OXIDATION C34 TO C55 MICROCRYSTALLINE WAXES UNDER CONTROLLED CONDITIONS, EACH PER ONE THOUSAND BARRELS OF PETROLEUM DISTILLATE. 